Smashing flashing

One of the more hidden, but critical, systems on a house is the moisture management system known as flashing. Channeling moisture away from the wood extends the life of the structure and reduces the likelihood of mold developing, so its kinda important. So besides adding galvanized steel Z-flashing to the bottom of the trailer to protect the plywood sheathing edge, I focused a lot of my attention on the trailer’s wheel wells.

I think that after the roof and windows, the wheel wells have the greatest potential for leaks and ensuing water damage. The Tumbleweed trailer, despite being designed with tiny houses in mind, doesn’t have a flashed option for the wheel well fenders, a real design flaw in my opinion. The fenders are curved to boot, making the sheathing more difficult to fit and cut without big gaps – angled would have been better. To address my gaps and to add more wood depth for the flashing I’d be attaching from outside, I cut four plywood gussets and caulked and nailed these to the inside of the wells.

Mind the gaps
Mind the gaps

I couldn’t find any pre-made flashing product to curve around the fenders, so I came up with my own system using 3″ L-flashing cut at the web and hand-bent to the radius of the fenders.

Snip N Bend
Snip N Bend

After caulking the outside seams where the fender and sheathing meet, I attached squares of flashing to cover the gaps I’d made on the curved pieces and screwed it all to the sheathing using flat head lathing screws. It was a very iterative process getting the flashing to mold to the fender, but it the end it all came out pretty well and hopefully pretty water-proof.


All this work will largely disappear under the Tyvek wrap that’s coming next. After that – windows!

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